Sedimentation apparatus



Y 0d. 14, 1941. C, SCOTT 2,259,230

SEDIMENTATION APPARATUS Original Filed March 26 1939 5 Sheets-Sheet 1 Oct. 14, 1941. v C H SCQTT v v 2,259,230

SEDIMENTATION APPARATUS Original Filed March 26, l939 3 Sheets-Sheet 2 ,f

Oct. 14, 1941.

Original Filed March 26, 1939 C. H. SCOTT SEDIMENTATION APPARATUS 3 Sheets-Sheet I5 FIGZ /39 g INVENTOR CHA/w 1S H. 6 C0 7 7',

Patented Oct. 14, 1941 Um'risp!` STATES PMI-:1W oFFlcE SEDIMENTATION APPARATUS Charles H. Scott, Westport, Conn., assignor to T he Dorr Company, Inc., New York, N. Y., a vcorporation of Delaware l/tefiled for abandoned application Serial No. j 264,262, March 26, 1939. This application March 12, 1940, Serial No. 323,529.

Britain May 19, 1939 11 claims.i

turnable about a vertically-extending axis. Such l ment.

apparatus is known that comprehends, (l) a main raking mechanism movable about a vertically-extending axis in closed circular paths over a circular section of the tank bottom and provided forftransferring sedimented material from diverse portions of the circular bottom section of the tank to a sediment discharge means leading from a lower interior portion of the tank, and (2i, acorner-exploring and cleaning mechanism disposed for successively operating over or within the outlying angular or corner sections that are proximate and extend beyond the circular section of the tank bottom, for. example, exploring mechanism disposed for successively Vengaging sedimented material in the several cornerA sections and for transferring the sedimented material engaged thereby from the diverse portions of the successive corner sections to the central f floor section from whence it is ultimately transferred to the sediment discharge by the functioning of the raking mechanism. I

One object of this` invention is to provide a sim-ple and positively acting sediment conveying corner-exploring device cooperatively associated is attained by imparting to the exploring element a crank-controlled movement, the crank arm performing a number of complete-revolutions or cyc'es during each complete revolution of the carrier, which is equal to the number of corners of the polygonal settling area served by the mech anisrn. y

According to one feature, gearing is cooperatively associated with the crank and with drive means for the carrier, so that thel number of crank revolutions per one revolution ofthe carrier, is equal tothe number of corners of the polygonal settling area. y

In one embodiment the carrier isV rotatively supported on a pier and the drive means com In Great fixed to the pier and consequently, with respect to the vertical rotary axis of the carrier. Power transmission means are associated with the carrier on the one hand and with the fixed gear on the other h and for positively turning the carrier, while the exploring element has imparted thereto positively controlled movement through properly geared transmission means operatively connecting the drive means with the exploring ele- As illustrative of the manner in which the invention hereof may be structurally embodied in an apparatus or unit of the class referredl to, reference is made tothe accompanying drawings 15 constituting a part ,of this specification.

A embodiment illustrated by Fig. 1,;

Fig. 3 is a perspective view of an end portion of a main raking arm or main sediment-raking member employed in the embodiment of Fig. 1

and Fig. 2; Fig. 4 is a view, diagrammatically illustrating various positions oi a corner-exploring element and of ay novel actuating mechanism thereforv when functioning within a'relatively square tank or as otherwise expressed when operating over f the successive cornered iioor portion of theV tank bottom;

Fig. 5 is a view' diagrammatically illustrating the various positions of a comer-exploring element and ofthe actuating mechanism therefor when functioning over and within the successive apex or cornered sections of an equilateral and equiangular iioor area or polygonal operating space typiedby one which is hexagonal;v

Fig. 6 is a view taken upon the' line 6--6 in 40 Figs. land 2, and showing the more detailed and amplified structure of the rotarymounting and drive for the main rotary carrier of the mechanism; 'i

Fig. 7 is an enlarged detailed sectional view of the crank arms controlling the movement of the corner exploringv element, as taken on line 1-1 'in Fig. 2;

Fig. 8 is a further enlarged and further detailed"sectional view as taken on line 8--8 in Fig. 7 showing a', pivot connection between 'a prise a force-resisting member or gear which is controlling crank arms in an arrangement and 2 position taken from Fig. 4, Fig. 10 being an enlarged detailed section taken along the line |0 in Fig. 9.

Reference will now be made tothe drawings in detail.

The sedimentation unit shown in plan in Fig. 1, of which certain sections of the tank or basin have been broken away, includes a cornered noncircular settling tank or sedimentation basin and a horizontally-turnable sediment-raking assemblage I2. The invention hereof is particularly useful in connection with tanks or basins of which the relatively fiat or straight inner surfaces I3 of themarginal wall I4 are disposed substantially after the order of the faces of a'n equilateral and equiangular polyhedron, or in which the fioor. area to be raked is inthe form of an equilateral and equiangular polygon which may be in the form of a triangle, square, pentagon, hexagon, septagon or octagon. In general,

however, when employed in sedimentation units it will be in connection with square, hexagonal or octagonal tanks or basins or in tanks or basins having square, hexagonal or octagonal floor areas to be raked. The tank or basin Il of Figs. 1 and 2 is of the form which is'usuallylreferred to as a square tank. This statement applies is employed which is operatively associated therewith. By way of example the motivated element may be a. main driving worm or strong endless screw 2| that is carried on or functionally embodied in 'the raking assemblage as a part thereof. This motivated worm or endless screw meshes with the teeth of the fixed gear whereby as the worm or screw turns it bodily moves about the fixed gear thus imparting the horizontal turning movement to the raking assemblage I2.

In the construction shown the main worm or endless screw 2| is on and driven through the medium of a horizontal shaft 22 that is part of the motivated mechanism that has motor 23 as the actuating means therefor and speed re-V ducing and power transmitting gearing 24 for driving the shaftl 22 from the rotor of the motor.

As tothe horizontally-turnable raking assembly I2, this in the embodiment shown comprises a carrier having a movable bearing 3| turnably mounted on the stationary supporting bearing I8. 'I'his turnable bearing 3| thus serves as the medium by which the carrier and all parts thereof or supported therefrom derive ultimate even though there is a fillet or corner filling section' I5 at each apex or cornered section of the tank wall. In this connection it should be noted that each apex or cornered section of any other equiangular and equilateral polygonal form or area with which the` invention hereof is employed has a fillet or curved corner nlling section I5. Moreover, for each fillet the arc shapedl face or curved marginal line thereof merges into the relatively iiatface portions or relativelyl straight defining linesadjacent thereto but upon opposite sides of the particular fillet.

In the embodiment of Figs. l and 2 the tank bottom hasa central circular section that is defined and located, for example, -within the circular lines 2, 4, 5, 6, 6a, etc.

This circular floor section slopes downwardly and inwardly toward a central sump or depressed sediment-discharge I6, located at or adjacent a fixed central pier or stationary supporting structure I'I rising from the bottom of the tank or basin. r Proximate and extending outwardly from the circular central floor section there are located the apex or cornered fioor sections delineatedffor example, by lines such as 4, 2, 1, 8, and 9. The surface of each of the cornered floor sections is horizontal or substantially so since that is the preferred form of construction where there is employed a corner-exploring and raking element that is mounted and actuated vaccordingv to the invention thereof.

A member'providing astationary bearing |3- is carried by or embodied in the pier or stationary structure I1. A fixed torque absorbing or stationary force-resisting member I9 which may be in the form of'a gear is fixed to the pier or stationary structure I1.,l The horizontally,-

turnable raking assemblage I2 derives its support from the `stationary bearing I8l and the fixedA torque-absorbing gear or stationary torque-resisting member 'I8 constitutes part of a motoractuatedl mechanism 2|! that is employed for turning the raking assemblage about a vertical-l ly-extending main axis which coincides with the geometrica-1 axis ofthe stationary bearing and the central pier. When a fixed gear as I9 is employed as the torque-resisting and absorbing member, then a motivated gear type of element support from the stationary structure and at the same time provides an arrangement of parts whereby the raking assemblage can turn about the vertically-extending central axis as and when the motor operates.

The horizontally-turnable carrier 30 4embodies orprovides a depending central body or body portion 50 and a radial carrier arm 32 extending therefrom outwardly toward the marginal wall of thetank. The carrier arm is ofsuch shape land length as to permit an unobstructed full turning movement in closed horizontal paths about the carrier axis. The comer-exploring element which has heretofore been referred to is designated by the reference character 33. It is ski-shaped and has a curved toe portion 34 and a relatively straight body portion `35. It is supported from the outer end of the carrier arm 32 through the medium of small worm gears 36-36 that rest upon bearing members provided on the arm, vertical shafts 31-31 secured to,

a depending position from the outer or swinging ends of the cranks or links 39.

Thel shaft 22-to which this main driving worm Y 2 lis secured extends along the carrier arm 32 and is mounted therefrom through the medium of bearingsprovided in sets of lateral extensions l 25-25, 26-26 and 21,-21. The horizontal shaft 22' is mounted so that it can turn in said bearinge and is secured against longitudinal movement in said bearings; in other words, so that there is permitted at the'most only a limited amount of longitudinal movement'` of or horizontal play for the shaft. The yshaft 22 has mounted thereupon and so as to be driven thereby two small worms or endless screws 4I-'-4| which mesh with the corresponding small worm gears 36-36, sometimes referred to as crank gears. From what has preceded, it will be manifest that as the shaft 22 turns it imparts uniform turning movements to thev worm gears 36-36, the shafts 31-31 and the cranks or crank elements 39--39 and consequent successive in and out horizontal movements to the cornerexploring element or ski-shaped member 33.

The 'shafts 31-31 are disposed a. suillcient horizontal distance apart to permit a full turning movement of each crank or link 39 carried thereby about the vertical axis corresponding thereto without experiencing any interference,

with the other crank or shaft carrying the same. The vertical axes about which the shafts l| 3'| and the cranks or crank elements 39-38 turn are sometimes referred to herein as secondary vertical axes that are horizontally-spaced from"the ".lhismeansvv main axis and also from each other.

that in the construction shown `one vertical shaft 31 is outwardly disposed from the main vertical` axis a greater distance than the other shaft. In

short, the horizontal distance between said crank shafts 31-31 is somewhat greater than the radial length of either of said cranks.

approximately along the same radial line. v

rThe shafts 31-31 being vertical and the pivotal connections 40-40 at the outer endsof the cranks being at the same elevation, it will be manifest that the corner-exploring element will move in horizontal paths as the cranks turn.

The gearing which embodies the worms and vindicates .the total length of throw which the cranks should have for imparting to the comerexploring elementv the afore-described successive epicycloidal movements. Thevapproximate length of each of the cranks should therefore be one-third of the length of the line 3-i0. 'I'he geometrical system just described can be employed for determining the length, or approxi- I `mate length of crank for operating a corner-ex- The cranks are lthe same length.v In the construction shown the vertical shafts 31 are disposed worm gears mentioned is proportioned and timed so that for each complete turning movement of the carrier and carrier arms about the main vertical axis there is completed a number of turns of each of the small worm gears 36-36, or what is the same thing a number of complete turns of each of the cranks 39-39 relative to the carrier arms, equal to the number of the cornered or apex sections of the particular polygonal area or space over or in which the raking assemblage operates. In the instance of the square tank of Fig. l the cranks move thecorner-exploring element through four complete but successive epicycloidal movements. During each complete epicycloidal movement the comer-exploring member moves from an innermost retracted position, to wit, from the central portion of a at inner face or straight marginal line rst progressively outwardly until it reaches full extended positionl within .and at the apex portion of the cornered section and thereafter progressively inwardly until it reaches its subsequent innermost retracted position by the time the corner-exploring element has arrived opposite the central portion of the succeeding fiat face or straight marginalline.

In designing a corner-exploring mechanism with a corner-exploring element so that the outermost end thereof will have successive relatively long straight line movements along each of the straight lines or fiat face portions and successive relatively short `movements along the relatively short curved or approximately arcuate region at the llet or filled in corner section between adv I.iaeentflat surface or straight line section of the polygonal surface or area, it becomes necessary to adopt a 'proper length for the cranks by which the corner-exploringelement is carried.

' This length may be geometrlcally determined as follows:

' Take the short radius of the polygonal figure,

or as otherwise expressed, the radius of the circle to which the 'flat faces or straight sides of the polygonal figure are tangent and extend the cant of a degree angle of a circle of whichthe radius 0--1 is indicated by R; and

ploring element within or over any cquilateral equiangular polygonal space or area. It also rel suits in a relatively straight line movementfor the outer end of the corner-exploring element 33 except for the movement along the relatively 4short curved fillet or arc-shaped portion.

The geometrical system of determining the operative length of the cranks 39 has been described in connection with a square or four-sided tank. 'I'he same scheme, however, can be employed to illustrate a trigonometrical method of determining the crank length. e

In this connection with the trigonometrical method it will be noted:

(a) That the tank has N number of cornered sections or apex portions and in the case of a square tank N is 4;

(b) That the angle equal toe 180 number of cornered sections` degrees;

(c) That the line ii-IU (see Fig. l) is the se- (d) That the length in'inches of each crank 39 is equal to product of R in inches multiplied by the value of the trigonometrical secant of a 45 degree angle as taken from the table of 'trigonometrical functions, from which product then is thereafter subtracted the number of inches of R. and which remaining difference is then divided by 3.

A general formula for any type ofv equilateral equiangular polygonal gure is trigonometrically expressed as follows:

In said formula:

R=theA short" radius in inches of the polygonal figure, or as otherwise expressed, is the radiusI of a circle inscribed in the polygonal figure and tangent to the straight sides-- or faces of the polygonal figure;

x=the length in inches of one-half of the Crank For polygonal figures having 3, 4, 6 or 8 sides said equation for determining the length of X becomes respectively as follows and furthermore.

when R is taken as unity, then the equation assumes a still more simple form as is clear from the formulas expressed below.

When determining crank lengths for use in connection with: Triangular polygonal figures then- Octagonal polygonal figures then-` (1.0824-1)=.027 the unit length or .027R For the length of each of the cranks 39-39 it is in order to adopt substantially the length educed by the general triogonometric formulae expressed. Nevertheless, this may be departed` therefrom or modified to a limited extentand still obtain the substantially desired movements of the outermost end of the corner-exploring element along polygonal paths which have relatively straight sides included in equilateral paths of which the apex portion is modified so to speak by the short curved or arcuate sections heretofore referred to. In this connection, it will be noted that lengthening of the crank results in causing the outermost limit of travel of the corner-exploring element to be further outwardly from the main vertical axis particularly for the movements in and adjacent the apex Iportion of the polygonal surface or area served thereby, and conversely shortening of the cranks results in lessening of' the outermost limits of movement for the exploring element, particularly in the general region of the apex sections of the polygon spaces or areas.

It will be understood' fromthe foregoing that the number of revolutions of the cranks 39 per one revolution of the carrier arm 32 must be equal. to the number of corners ofthe polygonal settling area to be served by the ,mechanismv Consequently, the ratio of the worm gear I9 to each of the worm gears 36 must be 4:1, provided both the worm 2l and the worms 4I are of the single threaded type.-

While the invention hereof primarily revolves `about and essentially relates to the corner-exploring mechanism, already fully described, nevertheless, a'specic and particular application thereof is its employment in and embodiment as part of a sediment-raking assemblage forraking and co1- lecting sediment from substantially all of the various and diverse sections of a tank bottom or area over which the assemblage horizontally turns and for transferring the raking sediment to a sediment discharge leading from the tank. The sediment raking assemblage therefore embodies the corner-exploring mechanism which engages sediment within and transfers sediment from the cornered sections or areas served thereby to a circular central section and it embodies a main rak-` ing mechanism which operates in horizontal circular paths over the central section and which functions to engage sediment that is on or within the central circular area toward and to the sed1.

pending body portion 50 of the carrier 30. The

outer end portion of the rake arm is shown in perspective in Fig. 3. It is formed of structural shapes such as rolled angles 5I, 52, 53 and 54 providing longitudinals that are connected into a relatively rigid structural formation by upper transverse tie members 55, 5B, etc., vertical tie members 51, 58, etc., diagonal brace elements such as 59, 60, 6I, 62, etc., and also by the raking blades 46, 41, 48, etc., previously referred to.

In order to complete a 'light but rigid shallow end construction for the rake arms the outer ends of the upper longitudinals 5I and 52 are bent down toward and connected to the corresponding lower longitudinals 5'3 and 54. An inspection of Fig. 3 I will make it clear that the rake arm 45 is a`skeleton type of box-like formation that is shallow,

wide, relatively strong and rigid and of a charac-l ter which will impart at the most only a slight local disturbance within the lower portion of thebody of relatively quiescent liquid within which it operates. An inspection of Fig. 1 will make it clear that this main raking mechanism functions over and serves to collect and'tran'sfer sediment over and within the' circular areas bounded by the circles I, 2, 3, 4, 5, etc., to wit, over an area bounded by a circle that is tangent within the straight side portion of the equilateral equiangular polygonal area or spaces served by the sediment raking assemblage as a whole. This main raking mechanism serves -or functions to convey to discharge sedimented materialthat has been passed to said central circular space or area by the corner-exploring `mechanism, and also -sediment originally deposited in or on said central circular space or area.

According to Fig. 1 and also. according to diagrammatic Figs. 4 and 5 the mainv carrier 30 or the radial carrier arm 32 thereof'moves in clockwise direction, as is indicated by the large arrows Aand the cranks 39which are carried from and move with but respect to the main carrier or carrier arm, turn in counterclockwise rdirections as is indicated by the arrows B.

In the construction shown in Fig. 1 the body portion 35. of' the' ski-shaped corner-exploring member 33 is connected to the swinging -or outer ends of the cranks in a manner whereby it is lo- -cated immediately or directly below the pivotal connections to the cranks.

It can be said that one of the gear actuated cranks orfcrank arms 39 would suffice to impart to the`corner-exploring element 33 the desired succession of inward and outward movements through the crank pin. or pivotal connection 0r pivot -portion 40, and that the other crank arm 39 and pivotal connection 40 in its function be considered as a guide means for the exploring element '33, both thefirst mentioned crank arm 39 andthe guide means then being coactive and veffective to determine the bodily movements'of the exploring element 33 along a predetermined Ipath. These guide means operatively connect a portion of the main carrier 30 (which portion is horizontally spaced from the locality of the In further deilnition'of these guide means it can .be said that they comprise a guiding member (namely an arm 39) on the main carrier 30 and a\ corresponding guided portion provided. on the exploring element 33,- and a ypivot portion 40 operatively interconnecting the guiding member and the guided portion.

'Ihe detailed sectional views in Figs. 7 and 8 show more clearly the pivotal connection 40 interconnecting the crank arms 39 and the cornerexploring velement 33. The pivotal vconnection I in particular is shown in Fig. 8 to comprise a pivot portion 40 fixed as by welding to the cornerexploring element 33, and rotatable in a bushing I 49h providedin the swinging outer end of the crank arm 39, and held in place by a collar 400 and cotter pin 40d. It will be understood that as a mere reversal of parts, the pivotal connectionV between the crank arms 39 and the corner-exploring element 33, may on the other hand comprise a pivot portion or crank pin that is fixed to the crank arm 39 and rotatable with respect to the corner-exploring element 33.

In th'econstruction shown in Figs. 4 and 5'the ski-shaped corner-exploring element is connected to the swinging or free outer ends of the cranks so as to have a general outward and forward inand which is normal or perpendicular to any side thereof is referred to as the short radius, and the length of this short radius is the same for both the truev and modied polygonal figures. The distance from the center of the true geometrical polygonal figure to an apex thereof is referred to as the long radius. The length of this long radius of the true geometrical figure is the one which should be employed in determining the length of a crank 39 according to the method hereafter referred to. This long radius is in fact thelength of the secant of the angle bounded by adjacent long and short radii. The length of each crank 39 for operating in any polygonal figure may be expressed as one-third of the dierential between the long andshort radii of the true geometricalv equilateral' equiangular polygonal figure, which differential is represented by the distance or line' 3--II (see Fig. 1). Each of the several fillets or arc-shaped sections Vof the modified figure occupies an area which comprehends as a marginal point thereof, a point which is inwardly located with respect to an apex of the true geometrical figure a distance substantially equal, or -approxlmately so, to one-third of the difference between the long and short radii ofthe true geometrical figure.

In connection with the sedimentation unit or apparatus described, it is in order to notethat The body of the ski-shaped emmne 33 is connected to the outerA oi swinging ends of the .Wcranks 39 in such a mannerthat when the crankof the inlying crank because that outer end is pivotally connected with a forward projection 63 supply means.

any suitable means for supplying liquid to the tank orbasin may be employed, as for example, a central feed which may involve a delivryof liquid into the central regions of the tank. Such feed may be through the central pier Il which may be hollow for providing an upow discharge withdrawal means all of which are old and well vknown in the sedimentation art. As is usual in l(see Fig. 4) provided on theski body and that portion of the ski body which is nearest the free end of the outlying crank 39 precedes or lies -ahead of the swinging or outer end of the outlying crank because that swinging end is pivotally connected i with a rearward projection 64 (see Fig. 4) provided on the body. In considering the foregoing remarks one should bear in mind that the gensize which does not have fillets or arc-shaped' formations at the apex thereof is herein referred to as a true geometrical equilateral equiangular polygon corresponding to the modified equilateral equiangular polygonal figure. In the equivalent true geometrical and modified polygonal figures sedimentation units or clarification apparatus of the type referred to the overflow weir determines the normal level of the liquid within the tank. In the construction illustrated the main portion of the. carrier arm 32 and also supporting bearing surface provided by stationary bearingl are located at elevations above that of the normal level of the liquid within the tank.

I claim z" l.-A sediment impelling and transfer mechanism for operating within a space defined by cornered sedimentation area which in plan is substantially equilateral, equiangular and polygonal, said mechanism comprising in combination a supporting bearing member providing a verticallyextendiiig axial center, a movable mainharrier 4any radius extending from the center of a ligure 75' mounted on said supporting bearing member for rcircular portion of the sedimentation area correspondlng to said closed path, horizontally-turnable crank elements supported from said main carrier, a corneraexploring sediment conveying element, a crank pin connection between said exploring element and the outer Aend of each of said c rank'elements and said conveying element disposed for operating over cornered' sections of the sedimentation area. that are proximate to but crank elements being timed through said gearing v with each other and with the movement of the main carrier in a manner to cause said corner. ex-

ploring element to move into and out of said cor-l nered sections so as to, convey sediment therefrom to said circularsedimentation area, as said main carrier turns.

2. A mechanism for operating over a polygonal settling area having cornered portions and comprising in operative combination and arrangement -a supporting bearing member, a movable main carrier mounted on said supporting bearing .member and rotatable about a. vertically-extending main axis determined, by said supporting bearing member land thus turnable in a horizontally-extending closed path about said axis, mo- 25 tivated mechanism for turning said main carrier about said main axis, a set of crank elements the inner end portions of which are turnably supported from the main carrier so as to move in ing secondary axis horizontally-spaced from and substantially parallel to the main axis and which secondary axes are spaced from each other a horizontal distance greater than the horizontal length tank define in plan anequilateral equiangular sedimentation area having rounded corners by virtue of which it represents a round-cornered equilateral equiangular sedimentation area as distinguished from an otherwise corresponding but relatively sharp-cornered equilateral equiangular polygonal figure the corners of which are represented by the angle of intersection-of the lines representing. the sides of the polygon, and

in which mechanism the effective length of each crank arm of the crank elements is approximately equal to one-third of the diierentlal in the length of the radii of the inscribed and the circumscribed circles of said relatively sharp-cornered equilat- `eral equiangular polygonal figure.

'7. An exploring sediment conveying'assemblage for av sedimentation tank or basin providing a polygonalsettling area which assemblage when in operating position with respect. to the tank comprises in operative combination and arrangement a supporting bearing fixed against turning movement with respect to the tank, a carrier ,Y turnably mounted on'said bearing for movement horizontal paths each about a vertically-extendelement i'lxed against turning Vmovement with re.-

of the crank elements whereby each crank element can make a complete turn without interference with the other, a comer-exploring sediment conveying element, a crank pin connection between said exploring element and the outer end of each of said crank elements, and gearing operatively associated with the motivated mechanism and with the crank elements, said gearing providing a ratio whereby each complete turning movement of the main carrier produces a number of comconvey sediment therefrom, as said main carrier turns.

3. A' sediment raking mechanism comprising plete revolutions of each crank element, equal to 4 5 the number of corners of the sedimentation area,

cause the said corner exploring element to move 50 into and out of said cornered sections so as to about a vertical main axis, a force-resisting gear spect to said supporting bearing, motivated mechanism comprising power transmission gearing Loperatively associated with said carrier on the one hand and said force-resisting gear element on the other`for positively turning. said. carrier `about said main. axis, a'secliment conveying rexploring element adapted for successive inward and outward movements with respect to said main axis for lconveying sediment from the corners of said settling area, actuating means for said exploring element, comprising a crank element mounted on said carrier and turnable about a secondary axis horizontally-spaced from the main axis and having a crank pin co-operativelyassociated with the exploring element so that the continuous turning of said crank element about its secondary axis imparts said successive movements to the exploring element, guide means operatively connecting a portion of said carrier, which portion is horizontally spaced from the locality 4of the mounting n of said crank element on said carrier, with a porthe features of construction as defined in and-by claim 2, wherein the main carrier includes a rake arm having fixed blades for operating over a circular area within the bounds of the polygonal varea over which the mechanism operates', which circular area is substantially tangetially associated with the sides of the onal area.

14. A mechanism as dened in and by claim 2,

polygonof said polyg- `wherein the gearing is designed, when the main carrier turns in aclockwise direction about the wherein the corner-exploring element in plan is revolutions of said crank element, equalto the 'f in the form of a ski having a straight main portermined by forward clockwise movement or the tion of said exploring element,l which latter portion is horizontally spaced-from the localityI of said crank pin, said guide .meansA comprising a guiding member on said carrier, a guided portion on said exploring element and cooperatively as-.

sociated with said guiding member in said successive inward and outward movements `of the exploring element, an operative connection includving a pivot portion .between the guiding member and the guided portion, whereby the exploring element is movable horizontally about said pivot portion while progressing bodily in said successive inward and outwardmovements as said crank elementv rotates, and gearingbeing cooperatively I associated with said crank element and with said motivated mechanism, and designed to provide a ratio whereby each 'complete turning movement Iof said carrier produces a number of `complete v sition in the tank comprises in operative combination and arrangement a stationary supporting lecting sediment over and from a cornered settling area, and having acarrierrotatable about a vertical main axis and over a circular portion or said bearing determining a vertical main axis, a carrier turnably mounted on said supporting bearing for horizontal movement about said axis, a

\ u iorce-lesiisting` member xedly positioned against turning movement with respect to said stationary supporting bearing, motivated power transmission means associated with said carrier on the one hand and said stationary force-resisting member on the other hand for positively turning said carrierjabout said axis, a corner-exploring element mounted for having imparted thereto successive outward and inward predeterminedbodily movements with respect to said main axis, crank elements mounted on said carrier and turnable about vertical secondary axes, that are horizontallyspaced from the main axis and having crank pins,

operatively engaging the corner-exploring element so that during the repetitiveturning thereof there is successively realized for the corner-exploring element with respect to the main axis an outward movement to a full extended position and an inward movement to an innermost retracted position, and gearing associated with the aforementioned motivated means and with the crank'` elements for continuously turning the latter while the carrier is turning about the main axis and at a constant ratio with respect to the turning movement of the carrier Labout the main axis, said ratio being such that each complete turning movement of the carrier is accompanied by a.

number. of complete revolutions of said crank ele-` ments, equal to the number of corners of said l polygon, the movements of said crank elements being timed through saidgearing with each other and with the movement of said .carrier in a manner to causesaid exploring element to move into and out of said corners, so as to convey sediment l, therefrom, as the carrier turns.

9. In a sediment conveying mechanism for colsaid' pivotal connection, said guide means com-- uprising a yguiding member on said carrier, a guid- Vsettling area, land also having drive means for rotating the carrier, acorner exploring device operatively mounted upon` said carrier for collecting sediment from the corner portions olfl the settling area into the circular portion thereof, and comprising a corner exploringr element, an arm mounted' on said carrier, to turn horizontally about a verticaliaxis, a pivotal vconnection to mount the exploring element on said arm, to turn about a vertical axis, guide means operatively connecting a portion of said carrier, which portion is horizontally spaced froml the locality of the mounting of said arm on said carrier, with a lportion of said exploring element, which latter portion is horizontally spaced from the locality of ed portion on said exploring element and cooperatively associated with said guiding member for causing successive inward and outward movements of the Vexploring element with respect to the vertical main axis of the carrier, an operative connection including 'a pivot portion between the -guiding member andthe guided portion of the exploring element, whereby the exploring element is movable horizontally about said pivot portion While progressing bodily in said successive inward Iand outward movements as said arm rotates, and

control means comprising driven means connected to the arm, motion transmitting means driven by said carrier drive means ,for drivingsaid drivenA means, for continuously turning said arm a number of complete revolutions relative to the carrier for each revolution of the'carrler, whereby said exploring element is caused to move alongl a pathway dei-lning a cornered area from which sediment is thereby removed as the carrier rotates.

I 10. Apparatus according to claim 9, in which said guiding means comprise anarm one endV of which `is pivotally mounted on said carrier, and upon the'othe'r end of which is pivotally mounted said exploring member.

` 11. Apparatus according to claim 9, infwhich the motion transmitting means` comprise gear means effective between said carrier drive means and said driven means connected to the arm.

CHARLES H. SCOTT. 

